• Assembling an Effective, Efficient Computer System

8/14/2019 Assembling an Effective, Efficient Computer System

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Principles of Information Systems, Seventh Edition 2

Assembling an effective, efficient computer system

requires an understanding of its relationship to the

information system and the organization. The computer

system objectives are subordinate to, but supportive of,

the information system and the needs of the

organization

Describe how to select and organize computer system

components to support information system (IS)

objectives and business organization needs


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When selecting computer devices, you also must consider

the current and future needs of the information system andthe organization. Your choice of a particular computer

system device should always allow for later improvements

Describe the power, speed, and capacity of central processing

and memory devices

Describe the access methods, capacity, and portability of

secondary storage devices Discuss the speed, functionality, and importance of input and

output devices

Identify popular classes of computer systems and discuss the role

of each


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Computer Systems: Integrating the

Power of Technology

Computer system

Special subsystem of an organizations overall information

system

Integrated assembly of devices used to input, process, store,

and output data and information

Hardware

Any machinerymost of which use digital circuitsthat

assists in the input, processing, storage, and output

activities of an information system


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Hardware Components

Central processing unit (CPU)

Input devices

Output devices


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Hardware Components (continued)

Communications devices

Primary storage devices

Secondary storage devices


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Figure 3.1: Computer System

Components



Hardware Components in Action

Step 1: Fetch instruction

Step 2: Decode instruction

Step 3: Execute instruction

Step 4: Store results



Figure 3.2: Execution of an Instruction



Processing and Memory Devices:

Power, Speed, and Capacity

System unit: houses the components responsible for

processingthe CPU and memory

All other computer system devices are linked either

directly or indirectly into the system unit housing



Processing Characteristics and

Functions

Machine cycle time is measured in:

Microseconds (1 millionth of a second)

Nanoseconds (1 billionth of a second)

Picoseconds (1 trillionth of a second)

MIPS (Millions of Instructions Per Second)



Processing Characteristics and

Functions (continued)

Clock speed: electronic pulses that affect machine cycle

time

Hertz (Hz): one cycle (pulse) per second

Megahertz (MHz): millions of cycles per second

Microcode: elementary circuits and logical operations aprocessor performs when executing instructions



Figure 3.3: Clock Speed and the

Execution of Microcode Instructions



Wordlength and Bus Line Width

Bit: a binary digit (0 or 1)

Wordlength: number of bits the CPU can process at any

one time

Bus line: physical wiring that connects the computer

system components



Physical Characteristics of the CPU

CPU: collection of digital circuits

Electrical current flows through silicon

Moores Law:

transistor densities on a chip double every18 months

Superconductivity: property of certain metals that allows

current to flow with minimal electrical resistance

Optical processors: computer chips that use light waves

instead of electrical current to represent bits



Figure 3.4: Moores Law



Complex and Reduced Instruction Set

Computing

Complex instruction set computing (CISC): chip

design that places as many microcode instructions into the

central processor as possible

Reduced instruction set computing (RISC): chip

design that involves reducing the number of microcode

instructions built into a chip to an essential set of

common microcode instructions



Memory Characteristics and Functions:

Storage Capacity



Types of Memory

Random access memory (RAM): temporary and volatile

Types of RAM

EDO (Extended Data Out)

DRAM (Dynamic RAM)

SDRAM (Synchronous DRAM)



Types of Memory (continued)

ROM (read-only memory): usually nonvolatile

Types of ROM

PROM (programmable read-only memory)

EPROM (erasable programmable read-only memory)

Cache memory High-speed memory that a processor can access more

rapidly than main memory



Figure 3.5: Basic Types of Memory Chips


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Figure 3.6: Cache Memory


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Multiprocessing

Multiprocessing: the simultaneous execution of two

or more instructions at the same time

Massively parallel processing

Speeds processing by linking hundreds or thousands of

processors to operate at the same time, or in parallel

Can coordinate large amounts of data and access them

with greater speed


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Figure 3.7: Massively Parallel Processing


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Secondary Storage

Secondary storage: offers advantages of nonvolatility,

greater capacity, and greater economy

Access methods, storage capacities, and portabilityrequired are determined by the information systems

objectives


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Table 3.1: Cost Comparison for Various

Forms of Data Storage


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Access Methods

Sequential access: retrieval method in which data must

be retrieved in order; devices used are called sequential

access storage devices (SASDs)

Direct access: retrieval method in which data can be

retrieved in any order; devices used are called direct

access storage devices (DASDs)


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Secondary Storage Devices

Magnetic tapes

Magnetic disks

Virtual tape

Optical discs


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Secondary Storage Devices

(continued)

Digital versatile disk (DVD)

Magneto-optical (MO) disks

Memory cards

Flash memory

Expandable storage


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Enterprise Storage Options

Attached storage

Network-attached storage (NAS)

Storage area network (SAN)


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Figure 3.12: Storage Area Network


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Input and Output Devices: The

Gateway to Computer Systems

Through input and output devices, people provide data

and instructions to computer and receive results from it

Selection of input and output devices depends on

organizational goals and information systems objectives


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Characteristics and Functionality

Data: can be human- or machine-readable

Data entry: process of converting human-readable data

into machine-readable form

Data input: involves transferring machine-readable data

into the system

Source data automation: involves capturing and editing

data where the data is initially created and in a form that

can be directly input to a computer


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Input Devices

Personal computer input devices

Keyboard

Mouse

Voice-recognition devices

Digital computer cameras

Terminals


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Input Devices (continued)

Scanning devices

Optical data readers

Magnetic ink character recognition (MICR) devices

Point-of-sale (POS) devices

Automated teller machine (ATM) devices


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Input Devices (continued)

Pen input devices

Light pens

Touch-sensitive screens

Bar-code scanners

Radio-frequency identification (RFID)


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Output Devices Display monitors

Liquid crystal displays (LCDs)

Active-matrix

Passive-matrix


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Output Devices (continued) Organic light-emitting diodes (OLEDs)

Printers and plotters

Computer output microfilm (COM) devices

Music devices


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Computer System Types, Selecting,

and Upgrading

Computers can be classified as either special purpose or

general purpose

Special-purpose computers: used for limitedapplications by military and scientific research groups

General-purpose computers: used for a wide variety of

applications


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Computer System Types

Handheld computers

Portable computers

Thin client

Desktop computers


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Computer System Types (continued)

Workstations

Servers

Mainframe computers

Supercomputers


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Selecting and Upgrading Computer

Systems

Hard drive considerations

Main memory considerations

Printer considerations

DVD burners


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Summary

Hardware: machinery that assists in the input,

processing, storage, and output activities of an

information system

Hardware components include central processing unit(CPU), input and output devices, communications

devices, primary storage devices, and secondary

storage devices

Random access memory (RAM): temporary and volatile

Read-only memory (ROM): usually nonvolatile


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Summary (continued)

Multiprocessing: simultaneous execution of two or more

instructions at the same time

Sequential access: records must be retrieved in order

Direct access: records can be retrieved in any order

Examples of secondary storage devices: magnetic tapes

and disks, optical disks, and DVDs

Enterprise storage options: attached storage, network-

attached storage (NAS), and storage area network (SAN)


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Summary (continued)

Examples of input devices: keyboards, mice, voice-

recognition devices, terminals, scanning devices, and

touch-sensitive screens

Examples of output devices: display monitors, liquidcrystal displays (LCDs), printers, and plotters

Computers can be classified as either special purpose or

general purpose

Computer system types: handheld computers, portable

computers, desktop computers, workstations, servers, etc.

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